fbpx

Susan Brown

Forum Replies Created

Viewing 15 posts - 1,756 through 1,770 (of 1,968 total)
  • Author
    Posts
  • in reply to: Current flow through loads #13918
    Susan Brown
    Keymaster

      Be careful about that expression “path of least resistance”. If there is a path of NO resistance, such as a wire with a closed switch, then all of the current will flow through that instead of through a load. This is a “short”.

      However, if there are two or more paths for current to flow, which all have loads, then some current will flow through all of them, not just the path with the least resistance.

      I don’t know what the “120 volts” means at the end of your sentence – would you please explain?

      in reply to: Unit 2 Quiz – need help on question 4 #13915
      Susan Brown
      Keymaster

        Hi Angel,

        “Constant duty cycle” means that the frequency of those square wave peaks are always the same. Does that make sense?

        in reply to: Current flow through loads #13914
        Susan Brown
        Keymaster

          The big question is: DOES current flow through the main coil with the detector switch closed.

          in reply to: Unit 3 – Parallel Circuits question #13910
          Susan Brown
          Keymaster

            Hi Kelly,

            We’re glad to help! Can you tell me which video (there are 3 in that unit) this is, and the timestamp for that section?

            in reply to: question 9 #13903
            Susan Brown
            Keymaster

              Which measurement makes you conclude that L2 is missing?

              Also, back to what I was trying to lead you to. You already correctly said no work was being done by the element (zero voltage drop measurement across it).

              It takes current flowing through a good load to produce work.

              We’ve asked you to assume that the load (the element) is perfectly good.

              We’re measuring some voltage present, even if it’s not exactly what we know we should have.

              So what can we conclude at this point that we absolutely do not have happening in this circuit?

              in reply to: question 9 #13875
              Susan Brown
              Keymaster

                We’ve already told you that the element is good. We want you to assume that it is a perfect element. So if no work is being done, but we do know at least some voltage is present, what is the only other possible conclusion?

                in reply to: question 9 #13872
                Susan Brown
                Keymaster

                  In this question, we don’t need to think about the phase relationship of L1 and L2. It is true that 240vac is created by L1 and L2 being out of phase, but it isn’t necessary to talk about that for this question.

                  in order for heating element to do any work current must flow

                  That is correct. So, there’s a measurement of zero voltage drop across the element, and we’ve already told you the element is known to be good. So, what can we conclude about current flow in this circuit?

                  in reply to: question 8 #13871
                  Susan Brown
                  Keymaster

                    If you are the booster, you can obviously reach out and touch L1 without having to go through a load. But can you reach out to N without having to go through any other loads? (electrons will always take a path with no load if they have the option)

                    in reply to: Qestion 4 midterm #13870
                    Susan Brown
                    Keymaster

                      Yes, that’s correct. For loads in a series, the current is the same throughout the circuit. So when you know the current and the resistance of a load, the voltage drop is an easy V = I x R calculation.

                      in reply to: midterm exam/question 8 #13862
                      Susan Brown
                      Keymaster

                        Hi James,

                        Did you receive the email I had written back to you with comments on your Midterm?

                        I had explained which parts you got correct/incorrect on Questions 7 and 8.

                        And, yes, you must have timed out with Question 9.

                        Here’s part of what I said about 8:
                        Your answers for parts 1 and 2 are not correct (the ignitor and the booster). Are these in series or parallel with each other? Knowing that is the primary step towards getting the answer correct.

                        in reply to: Midterm Exam Question 8 #13833
                        Susan Brown
                        Keymaster

                          Exactly! Does that all seem clear to you now, or do you have any further questions?

                          in reply to: Midterm Exam Question 8 #13811
                          Susan Brown
                          Keymaster

                            If loads are in series, then they will split up the voltage proportional to their resistance.

                            AC power goes back and forth (rapidly) between L1 and N in a 120vac circuit like this, so a load needs a connection to both or else you don’t have a circuit.

                            You’re close, but not quite seeing where I’m going. Electrons will always seek a path with no load in it over one with a load in it. There is a special name for this situation – when there is an alternate path for current that has no load. Do you remember what that is called? Can you see how when the detector switch is closed, it creates this situation?

                            in reply to: Midterm Exam Question 8 #13795
                            Susan Brown
                            Keymaster

                              The booster goes through the detector so its 120 in VD, Right?

                              Yes. So then why would you think that the main will drop any voltage? Will any of the current that goes through the booster and/or ignitor also go through the main?

                              (We’re almost there!)

                              in reply to: Midterm Exam Question 8 #13792
                              Susan Brown
                              Keymaster

                                Zen trick: Become the Booster. It’s easy to see that you can touch L1 directly, without having to go through another load. What happens when you reach out to touch N? (Remember, electrons don’t see bends or turns in the circuit – they are just finding a path to the power source.)

                                in reply to: Midterm Exam Question 8 #13783
                                Susan Brown
                                Keymaster

                                  A good first step for this problem is to examine the layout of the circuits and determine if current is flowing through each load. What do you think?

                                Viewing 15 posts - 1,756 through 1,770 (of 1,968 total)